Gull-billed Tern

Gelochelidon nilotica

Besides the thick bill that gives it its name, this tern has a relatively stocky build and broad wings. Typically seen in leisurely flight over marshes, hawking for insects in the air or swooping down to take prey from the water or the ground; unlike typical terns, rarely dives into water for fish. On the ground, walks better than most terns. Widespread in warmer parts of the world, but local in North America, mainly in southeast. Generally found only in small numbers.

Conservation status

Evidently far less numerous on the Atlantic Coast today than it was historically. Human disturbance and loss of nesting sites among likely causes. Has begun nesting on rooftops in some Gulf Coast areas. Colonized southern California, apparently from western Mexico, beginning to nest at Salton Sea in 1920s and at San Diego in 1980s.

Salt marshes, fields, coastal bays. Restricted to seacoast in North America (except in Florida and at Salton Sea, California), but does most foraging over marshes, pastures, farmland, and other open country just inland from coast. Nests mostly on beaches, islands. Reportedly used to nest more often in salt marshes, abandoned those sites because of human persecution.

Besides the thick bill that gives it its name, this tern has a relatively stocky build and broad wings. Typically seen in leisurely flight over marshes, hawking for insects in the air or swooping down to take prey from the water or the ground; unlike typical terns, rarely dives into water for fish. On the ground, walks better than most terns. Widespread in warmer parts of the world, but local in North America, mainly in southeast. Generally found only in small numbers.

Photo Gallery

Feeding Behavior

Forages by flying slowly into wind, dipping to surface of land or water to pick up items, or by catching flying insects in the air. Sometimes forages while walking on ground; rarely plunges into water.

Eggs

2-3, sometimes 1-4. Pale buff, spotted with dark brown. Incubation is by both parents (although female may do more), 22-23 days. Young: Leave nest a few days after hatching, move to dense plant cover if nearby. Both parents bring food for young. Age at first flight 4-5 weeks. Young may remain with parents 3 months or more, beginning southward migration with them.

Young

Leave nest a few days after hatching, move to dense plant cover if nearby. Both parents bring food for young. Age at first flight 4-5 weeks. Young may remain with parents 3 months or more, beginning southward migration with them.

Diet

Mostly insects. Feeds on a wide variety of insects, caught on ground, in air, or at surface of water; also spiders, crabs, shrimp, mollusks, earthworms, marine worms, small fish, lizards, frogs, toads, rodents, small birds.

Nesting

Colonial breeder. Colonies usually small, not as densely packed as those of many terns. Has some aerial displays, but much of courtship display takes place on ground, involving elaborate posturing, bill-pointing, male feeding female. Nest site is on open ground, sometimes on gravel roof. Nest (built by both sexes) is shallow depression, often with rim of soil, addition of some plant material and debris.

How climate change could affect this bird's range

In the broadest and most detailed study of its kind, Audubon scientists have used hundreds of thousands of citizen-science observations and sophisticated climate models to predict how birds in the U.S. and Canada will react to climate change.

Gull-billed Tern

Each map is a visual guide to where a particular bird species may find the climate conditions it needs to survive in the future. We call this the bird’s “climatic range.”

The colors indicate the season in which the bird may find suitable conditions— blue for winter, yellow for summer (breeding), and green for where they overlap (indicating their presence year-round).

The darker the shaded area, the more likely it is the bird species will find suitable climate conditions to survive there.

The outline of the approximate current range for each season remains fixed in each frame, allowing you to compare how the range will expand, contract, or shift in the future.

The first frame of the animation shows where the bird can find a suitable climate today (based on data from 2000). The next three frames predict where this bird’s suitable climate may shift in the future—one frame each for 2020, 2050, and 2080.

You can play or pause the animation with the orange button in the lower left, or select an individual frame to study by clicking on its year.

The darker the color, the more favorable the climate conditions are for survival. The outlined areas represent approximate current range for each season. More on reading these maps.